Voltage converter having overcurrent protection

ABSTRACT

Voltage converter having overcurrent protection. In some embodiments, a voltage converter can include a voltage converting circuit configured to receive an input voltage and generate an output voltage. The voltage converter can further include an overcurrent protection circuit coupled to the voltage converting circuit and having a detection unit configured to detect an overcurrent condition associated with the voltage converting circuit. The overcurrent protection circuit can further include a consumption unit configured to selectively consume and thereby reduce a current in a path associated with the voltage converting circuit based on the detection of the overcurrent condition.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. application Ser. No.15/332,232 filed Oct. 24, 2016, entitled CIRCUITS AND DEVICES RELATED TOOVERCURRENT PROTECTION, which is a continuation of U.S. application Ser.No. 14/287,255 filed May 27, 2014, entitled OVERCURRENT PROTECTIONDEVICE AND OVERCURRENT PROTECTION METHOD FOR ELECTRONIC MODULES, thebenefits of the filing dates of which are hereby claimed and thedisclosures of which are hereby expressly incorporated by referenceherein in their entirety

TECHNICAL FIELD

The present application relates to a field of electronic circuits, andmore particularly, to an overcurrent protection device for electronicmodules and a corresponding overcorrect protection method.

BACKGROUND

Electronic modules such as a voltage converter, a power amplifier, amonitor or the like exist in various electronic apparatus, such astablet computers, smart phones, music players etc., and each electronicmodule has a rated current. When the current flowing in the electronicmodule exceeds the rated current, the electronic module will be burnedout and cannot work. Therefore, it is necessary to set an overcurrentprotection device in the electronic module so as to protect the entireelectronic module when the current flowing through it is too large.

The various electronic modules require a power source to supply power sothat they can work. Conventional overcurrent protection devices canachieve overcurrent protection by disconnecting the electronic modulefrom the power source. However, cutting off the power supply of theelectronic module may cause disturbance of its operation, and it isdifficult to restart the operation of the electronic module, which mayaffect operations of other modules or electronic circuits associatedwith the electronic module.

Moreover, in the conventional overcurrent protection devices,overcurrent protection can also be achieved by controlling an internalcurrent of the electronics module. However, it is difficult toeffectively perform overcurrent protection in some cases. Discussion isprovided below with the electronic module being a boost converter asexample.

The boost converter serves for converting a specific DC input voltageVin to a larger output voltage Vout so as to supply power to a functionmodule in the electronic apparatus. In the operation process of theboost converter, the input electricity is temporarily stored in anelectricity storage element such as an inductor, a capacitor and others(i.e., performing a charging process), and then the electricity isreleased at an output terminal with different voltages (i.e., performinga discharging process), so that the input voltage Vin is converted tothe desired output voltage Vout. The boost converter includes a controlelement such as a switch, and the control element is driven by a drivingsignal to control the charging and discharging process. When the currentin the boost converter is too large, the overcurrent protection devicedrives the control element to only discharge, not charge, so as toexpect a gradual decrease in the current of the storage device in thedischarge process.

The overcurrent protection device in the above boost converter canprotect the voltage converter well when the output voltage Vout issignificantly greater than the input voltage Vin. However, when theoutput voltage Vout is close to the input voltage Vin, or when the loaddriven by the boost converter is too heavy and the output voltage Voutis caused to be lower than the input voltage Vin, the current reductionamount on the electricity storage element will be very small, evennegative, i.e., it shows as a current increase on the electricitystorage element. This can be seen from the following Equation (1)

$\begin{matrix}{{\Delta\; I_{LD}} = {{- \frac{{Vout} - {Vin}}{L}} \cdot {Toff}}} & {{Equation}\mspace{14mu}(1)}\end{matrix}$where ΔI_(LD) is a current reduction amount on the electricity storageelement, Vout is an output voltage of the boost converter, Vin is aninput voltage of the boost converter, L is an inductance value of aninductor that serves as the electricity storage element, and Toff is aturn-off time during which the control element controls the electricitystorage element to discharge. It can be known from to Equation (1) that,when the output voltage Vout is close to the input voltage Vin, thecurrent decrease on the electricity storage element current is verysmall; when the output voltage Vout is lower than the input voltage Vin,the current decrease on the storage device is negative. Therefore, evenif the overcurrent protection device detects that the current in theboost converter is too large and turns off the control element tocontrol the current in the boost converter, it is still hard toeffectively reduce the current therein so as to perform overcurrentprotection on the boost converter. Here, failure of the overcurrentprotection device is described with the overcurrent protection device inthe boost converter as an example, there are similar problems inelectronic modules having a power input such as an amplifier, a monitoretc.

SUMMARY

Aspects of the present application may relate to an overcurrentprotection device, an electronic module (e.g., a voltage converter)including the overcurrent protection device, and a method forovercurrent protection.

The electronic module to which the overcurrent protection device of thepresent application is applied may include: an electricity storage unitfor temporarily storing input electricity and being capable of releasingthe stored electricity through an electricity transmission path; anelectricity storage control unit for controlling storage and release ofelectricity in the electricity storage unit. The electronic module forexample is a boost converter, an amplifier, a monitor etc.; theelectricity storage unit for example is an inductor in the boostconverter, a charge pump in the amplifier etc.

The overcurrent protection device of the present application can detectan overcurrent event that occurs in the electronic module, and enableovercurrent protection when it detects an overcurrent event. When anovercurrent event occurs, the overcurrent protection device of thepresent application not only can control the electricity storage unit tono longer store the input electricity through the electricity storagecontrol unit, but also set an electricity consumption unit on theelectricity transmission path on which the electricity storage unitreleases electricity, and use it to consume electricity stored in theelectricity storage unit, thereby reducing the current flowing in theelectronic module and achieving overcurrent protection. The electricityconsumption unit set on the electricity transmission path may be aspecifically set resistor, and may also be implemented by an electronicelement already existing in the electronic module.

By utilizing the overcurrent protection device of the presentapplication, it is possible to effectively carry out overcurrentprotection on the electronic module, rather than being limited by theoperation state of the electronic module. For example, even if theoutput voltage in the boost converter is close to or less than the inputvoltage, the current in the boost converter can also be reducedeffectively, thus implementing overcurrent protection.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly explain the technical solution, drawingsreferenced in the description of embodiments or conventionaltechnologies are briefly introduced below. The drawings described beloware merely some embodiments of the present invention, a person ofordinary skill in the art can also obtain other drawings according tothese drawings. Identical reference numerals typically indicateidentical components throughout these drawings.

FIG. 1 schematically illustrates a block diagram of the overcurrentprotection device in the present application;

FIG. 2 schematically illustrates an application example of theovercurrent protection device of the present application in anasynchronous boost converter;

FIG. 3 schematically illustrates a circuit diagram of an overcurrentdetection unit in the overcurrent protection device in FIG. 2;

FIG. 4 schematically illustrates an application example of overcurrentprotection device of the present application in a synchronous boostconverter;

FIG. 5 illustrates a schematic diagram of the relationship between agate-source voltage of the of triode and a drain current thereof in FIG.4;

FIGS. 6(a) and 6(b) schematically illustrate a circuit diagram of aclamping unit in the overcurrent protection device shown in FIG. 4;

FIG. 7 schematically illustrates a circuit diagram of a second drivingunit in the overcurrent protection device shown in FIG. 4;

FIG. 8 illustrates a schematic waveform of performing overcurrentprotection by the overcurrent protection device in FIG. 4 in thesynchronous boost converter; and

FIG. 9 illustrates a flowchart of an exemplary overcurrent protectionmethod in the present application.

DETAILED DESCRIPTION

The overcurrent protection device and the electronic module includingthe overcurrent protection device described herein can be realized in avariety of electronic apparatuses, which may include, but not arelimited to, an electronic product, a portion of an electronic product,an electronic test equipment etc. The electronic product may include,but is not limited to, a smart phone, a TV, a tablet computer, amonitor, a personal digital assistant, a camera, an audio player; amemory etc. A portion of the consumer electronic product may include amulti-chip module, a power amplifier module, a voltage converter etc.

FIG. 1 schematically illustrates a block diagram of the overcurrentprotection device 100 in the present application.

As shown in FIG. 1, an electronic module to which the overcurrentprotection device 100 is applied may include: an electricity storageunit 10 for temporarily storing input electricity and being capable ofreleasing the stored electricity through an electricity transmissionpath; an electricity storage control unit 20 for controlling a storageand a release of electricity in the electricity storage unit 10. Theelectronic module including the electricity storage unit 10 and theelectricity storage control unit 20 for example is a boost converter, anamplifier etc. The power transmission path is a path on which theelectricity of the electricity storage unit 10 is released. As anexample, in the voltage converter, the power transmission path is a pathbetween the electricity storage unit 10 and a port of outputtingvoltage, and the port of outputting voltage serves for supplying powerto load of the voltage converter; in the amplifier, the electricitytransmission path is a circuit path connected with an output of a chargepump. The boost converter, amplifier, etc. provided herein are merelyexamples of the electronic module to which the overcurrent protectiondevice is applied, any electronic module including an electricitystorage unit and an electricity storage control unit may adopt theovercurrent protection device in the present application.

The electricity storage control unit 20 controls the electricity storageunit 10 to receive input electricity from an input terminal Sin andtemporarily store the input electricity in the electricity storage unit10, correspondingly, the current that flows through the electricitystorage unit 10 increases gradually; thereafter, the electricity storagecontrol unit 20 controls the electricity storage unit 10 to release thestored electricity through the electricity transmission path. Thus, whenaccumulation of electricity is excessive in the electricity storage unit10, the output current will be extremely large, which will destroy theelectricity storage unit 10, the electricity storage control unit 20,and other electronic elements connected with the electricity storageunit 10 in the electricity transmission path, The electricity storageunit 10 for example is an inductor in the boost converter, a charge pumpin the amplifier etc., and the electricity storage control unit 20 forexample is a control switch in the boost converter, a control elementfor controlling the charge pump in the amplifier etc.

In FIG. 1, only units or sections in the electronic module that aredirectly associated with overcurrent protection device 100 areillustrated. In practice, the electronic module may also include otherunits or sections, for example, the voltage converter may furtherinclude a feedback unit for performing feedback control based on anoutput voltage, a voltage stabilizing unit for stabilizing the outputvoltage, and a driving unit for driving the electricity storage controlunit 20 etc. Units or sections included by an individual electronicmodule will vary depending on a different function of the electronicmodule.

As shown in FIG. 1, the overcurrent protection device 100 of the presentapplication may include: an overcurrent detection unit 110 fordetermining whether an overcurrent event occurs in the electronicmodule, outputting an overcurrent indication signal OCE indicative ofwhether an overcurrent event occurs, and supplying the overcurrentindication signal OCE to the electricity storage control unit 20 so asto control the electricity storage unit 10 to release electricity whenan overcurrent event occurs; an electricity consumption unit 120removably connected in the electricity transmission path and consumingelectricity that passes through the electricity transmission path whilebeing connected in the electricity transmission path; an overcurrentcontrol unit 130 for controlling connection of the electricityconsumption unit 120 in the electricity transmission path based on theovercurrent indication signal OCE.

The overcurrent detection unit 110 can for example detect a currentoutput from the electricity storage unit 10 of the electronic module,and determine whether an overcurrent event occurs in the electronicmodule by comparing the current output from the electricity storage unit10 with a preset current threshold. Typically, when the current outputfrom the electricity storage unit 10 is greater than or equal to thepreset current threshold, it is determined that an overcurrent eventoccurs in the electronic module; when the current output from theelectricity storage unit 10 is less than the preset current threshold,it is determined that no overcurrent event occurs in the electronicmodule. Alternatively, the overcurrent detection unit 110 can alsodetect voltage in the electricity transmission path, and determinewhether an overcurrent event occurs in the electronic module bycomparing the detected voltage with a preset voltage threshold. Variousways may be adopted for different electronic modules to determinewhether an overcurrent event occurs therein, specific determination waysdo not constitute a limitation to the embodiments of the presentapplication.

The electricity consumption unit 120 can be outside the electricitytransmission path when no overcurrent event occurs, and be connected inthe electricity transmission path to consume electricity when anovercurrent event occurs. As an example, the electricity consumptionunit may be a resistor, a load that consumes electricity, and so on. Anyelement that consumes electricity may be used as the electricityconsumption unit 120.

When the overcurrent indication signal OCE output by overcurrentdetection unit 110 indicates that an overcurrent event occurs, theovercurrent detection unit 110 supplies the overcurrent indicationsignal OCE to the electricity storage control unit 20 to control theelectricity storage unit 10 to release electricity and no longer receivemore electricity from the input terminal Sin.

When the overcurrent indication signal OCE output by overcurrentdetection unit 110 indicates that an overcurrent event occurs, theovercurrent control unit 130 controls to connect the electricityconsumption unit 120 in the electricity transmission path in order toconsume electricity and thereby avoid a continued increase of thecurrent output by the electricity storage unit, and accordingly protectthe electricity storage unit 10 and the electricity storage control unit20 and electronic elements in the electricity release path from beingdestroyed. For example, the overcurrent control unit 130 may control toattach the electricity consumption unit 120 in the electricitytransmission path as a bypass unit, such that when no overcurrent eventoccurs, current of the electricity storage unit 10 directly passesthrough the electricity transmission path without passing through theelectricity consumption unit 120, and when an overcurrent event occurs,the electricity consumption unit 120 is made to reside in theelectricity transmission path to consume electricity.

In the overcurrent protection device 100 described in conjunction withFIG. 1, when an overcurrent event occurs, as compared with aconfiguration where only the electricity storage unit 10 no longerstores the input electricity in the conventional technology, theelectricity consumption unit is further provided on the electricitytransmission path where the electricity storage unit 10 releaseselectricity, and electricity stored in the electricity storage unit 10is consumed by using the electricity consumption unit, which gradually,reduces the current flowing in the electronic module and therebyachieves overcurrent protection.

FIG. 2 schematically illustrates an application example of theovercurrent protection device 200 of the present application in anasynchronous boost converter. FIG. 2 shows the overcurrent protectiondevice 200 in the present application and a device in the asynchronousboost converter and connected with the overcurrent protection device200.

As shown in FIG. 2, the electricity storage unit 10 in FIG. 1 is formedby using an inductor L connected to a port that inputs voltage Vin. Atriode T_(N) and a first driving unit for the triode T_(N) are used asan electricity storage control unit 20 for controlling the inductor L.The electricity transmission path having a diode D thereon is formedbetween the inductor L and a port that outputs voltage Vout. Further,the asynchronous boost converter further includes a capacitor C used forstably outputting the output voltage Vout.

During a charging process, the triode T_(N) is turned on under controlof the first driving unit, i.e., a short circuit is formed between theinductor L and the ground to produce current. The diode D is turned offbecause voltage at its input is lower than voltage at its output, i.e.,an open circuit is formed between a connection point (i.e., point SW inFIG. 2) of the inductor L and the triode T_(N) and the port that outputsvoltage, and the capacitor C is prevented from discharging to ground.Since the input voltage Vin is a direct current, induction current inthe inductor L increases at a constant rate, and as the inductioncurrent increases, electricity is stored in the inductor L.

During a discharging process, the triode T_(N) is turned off undercontrol of the first driving unit, i.e., an open path is formed betweenthe inductor L and the ground; the diode D is turned on because thevoltage at its input is higher than voltage at its output, i.e., a shortcircuit is formed between the point SW in FIG. 2 and the port thatoutputs voltage. Because of a holding characteristic of the inductioncurrent, the current that passes through the inductor L will slowlydecrease from a value when the charging is completed, until a nextcharging process starts or the current value drops to zero. The voltagebetween two ends of the capacitor C increases, and boosting conversionis achieved.

A resistor R and a switch S of the overcurrent protection device 200 inFIG. 2 correspond to the electricity consumption unit 120 and theovercurrent control unit 130 of the overcurrent protection device 100 inFIG. 1, respectively. That is to say, the electricity consumption unit120 and the overcurrent control unit 130 in FIG. 1 are implemented byusing the resistor R and the switch S, respectively.

As shown FIG. 2, the overcurrent protection device 200 comprises: anovercurrent detection unit 110 for determining whether an overcurrentevent occurs in the electronic module based on the current in theinductor L (e.g., current at the point SW in FIG. 2), outputting anovercurrent indication signal OCE indicating whether an overcurrentevent occurs, and supplying the overcurrent indication signal OCE to thefirst driving unit to control the inductor L to discharge via the triodeT_(N); a resistor R removably connected in the electricity transmissionpath and consuming electricity that passes through the electricitytransmission path while being connected in the electricity transmissionpath; a switch S for opening when the overcurrent indication signal OCEindicates that an overcurrent event occurs, and connecting the resistorR in the electricity transmission path to consume electricity. Further,when the overcurrent indication signal OCE indicates that no overcurrentevent occurs, the switch S is closed, and a short circuit is formedthereby excluding the resistor R from the electricity transmission path.

FIG. 3 schematically illustrates a circuit diagram of an overcurrentdetection unit 110 in the overcurrent protection device 200 in FIG. 2.As shown in FIG. 3, current at the point SW in FIG. 2 is sensed by acurrent sensor, and converted to a sensed voltage Vsense to be output.The sensed voltage Vsense is compared with a preset reference voltageVref by a comparator CMP, and then logical operations are performed on acomparison result of the comparator CMP and a clock signal CLK by usingthree “NOR” gates NOR1, NOR2, NOR3, so as to obtain the overcurrentindication signal OCE. When the sensed voltage Vsense is less than thereference voltage Vref, an overcurrent signal OCE which is a high signalis output when the clock signal CLK is at a rising edge to indicate thatno overcurrent event occurs; when the sensed voltage Vsense is greaterthan or equal to the reference voltage Vref, an overcurrent indicationsignal OCE which is a low signal is output when the clock signal CLK isat a rising edge to indicate that an overcurrent event occurs. Asdescribed above, different modes may be adopted for different electronicmodules to determine whether an overcurrent event occurs therein, andspecific determination ways do not constitute a limitation to theembodiments of the present application.

When the overcurrent indication signal OCE output by overcurrentdetection unit 110 indicates that an overcurrent event occurs, theovercurrent indication signal OCE is supplied to the first driving unit,which drives the triode T_(N) to control the inductor L to releaseelectricity and no longer receive more electricity from the inputterminal, and to control the switch S to open and connect the resistor Rin the electricity transmission path in order to consume electricity andthereby avoid a continued increase of the current output by the inductorL, and accordingly protect the inductor L, the triode T_(N), the diodeD, and the load powered by the output voltage Vout from being destroyed.Here, the resistor R is only schematic, a light emitting element or thelike may also be employed as the electricity consumption unit, thusprompting occurrence of an overcurrent event while consumingelectricity.

When the overcurrent indication signal OCE output by overcurrentdetection unit 110 indicates that no overcurrent event occurs, the firstdriving unit normally drives the triode T_(N) to control the inductor Lto discharge or charge, the switch S is in a closed state, andcorrespondingly the two ends of the resistor R is made a short circuit,so that the resistor R is excluded from the electricity transmissionpath in the boost converter, and the normal operation of the boostconverter will not be affected.

In the overcurrent protection device 200 described in conjunction withFIG. 2, when an overcurrent event occurs, as compared with aconfiguration where only the inductor L is controlled to no longer storethe input electricity in the conventional technology, the resistor R isfurther provided on the electricity transmission path where the inductorL releases electricity, and electricity stored in the electricitystorage unit 10 is also consumed by the resistor R. In this case, evenif the output voltage in the boost converter is close to or less thanthe input voltage, the resistor R can also be used to effectively reducethe current in the boost converter and achieve overcurrent protection.

FIG. 4 schematically illustrates an application example of overcurrentprotection device of the present application in a synchronous boostconverter. FIG. 4 shows the overcurrent protection device 400 in thepresent application and an element in the synchronous boost converterwhich is connected to the overcurrent protection device 400.

The inductor L, the triode T_(N), the first driving unit for the triodeT_(N), and the capacitor C in the synchronous boost converter in FIG. 4are the same as the inductor L, the triode T_(N), the first driving unitfor the triode T_(N), and the capacitor C in the asynchronous boosterconverter in FIG. 2, respectively. The synchronous boost converter inFIG. 4 differs from the asynchronous boost converter in FIG. 2 in that:the diode D in FIG. 2 is replaced with the triode T_(p) in FIG. 4, andthe triode T_(p) is driven by a second driving unit, which serves forgenerating a high signal or a low signal to cause the triode T_(N) toturn on or turn off. In addition, the overcurrent protection device 400in FIG. 4 also differs in operation as described herein from theovercurrent protection device 200 in FIG. 2.

The charging process and the discharging process of the synchronousboost converter in FIG. 4 are similar to those of the asynchronous boostconverter in FIG. 2, respectively, which are briefly described below.

During a charging process, the triode T_(N) is turned on under controlof the first driving unit, i.e., a short circuit is formed between theinductor L and the ground to produce induction current, and the triodeT_(p) is turned off under driving of the second driving unit to yield anopen path formed between the inductor L and a port that outputs thevoltage Vout. Since the input voltage Vin is a direct current, inductioncurrent in the inductor L increases at a constant rate, and as theinduction current increases, electricity is stored in the inductor L.

During a discharging process, the triode T_(N) is turned off undercontrol of the first driving unit, i.e., an open path is formed betweenthe inductor L and the ground, and the triode T_(p) is turned on underdriving of the second driving unit, i.e., a short circuit is formedbetween the inductor L and a port that outputs the voltage Vout. Becauseof the holding characteristic of the induction current, the current thatpasses through the inductor L will slowly decrease from a value when thecharging is completed, and the voltage between two ends of the capacitorC increases correspondingly, that is, boosting conversion is achieved.

A clamping unit 131 of the overcurrent protection device 400 in FIG. 4corresponds to the overcurrent control unit 130 of the overcurrentprotection device 100 in FIG. 1. In addition, in FIG. 4, the electricityconsumption unit 120 is not specifically set in the overcurrentprotection device 400. Instead the triode T_(p) in the synchronous boostconverter is used for consuming electricity in the electricitytransmission path when an overcurrent event occurs. That is to say, theelectricity consumption unit 120 and the overcurrent control unit 130 inFIG. 1 correspond to the triode T_(p) and the clamping unit 131 in theovercurrent protection device 400 of FIG. 4, respectively. In FIG. 4,the triode T_(N) is an N-type triode, the triode T_(p) is a P-typetriode, which are just examples. Other types of triode may be used asthe triodes T_(N) and T_(p), the specific type of each triode does notconstitute a limitation to the embodiments of the present application.

As shown in FIG. 4, the overcurrent protection device 400 may include:an overcurrent detection unit 110 for determining Whether an overcurrentevent occurs in the synchronous boost converter based on the current inthe inductor L (e.g., current at point SW in FIG. 4), outputting anovercurrent indication signal OCE indicating whether an overcurrentevent occurs, and supplying the overcurrent indication signal OCE to thefirst driving unit to control the inductor L to discharge via the triodeT_(N); a triode T_(p) whose source and drain are connected in theelectricity transmission path, and whose gate is connected to a seconddriving unit; a clamping unit 131 for clamping the gate of the triodeT_(p) at a predetermined voltage when the overcurrent indication signalOCE indicates that an overcurrent event occurs and thereby increasing aresistance value of the triode T_(p) so as to consume the electricity inthe electricity transmission path. The predetermined voltage may be theinput voltage Vin, or a predetermined value smaller than the inputvoltage Vin. When the overcurrent indication signal OCE indicates thatno overcurrent event occurs, the clamping unit 131 does not clamp thegate of the triode T_(p), and the triode T_(p) operates normally as atriode in the synchronous boost converter. The overcurrent detectionunit 110 in FIG. 4 is the same as that described in the above inconjunction with FIGS. 1-3, an thus no details are repeated here.

Principle of clamping the gate of the triode T_(p) at the predeterminedvoltage to increase the resistance value of the triode T_(p) will bedescribed below in conjunction with FIG. 5. FIG. 5 illustrates aschematic diagram of the relationship between a gate-source voltage Vsgof the triode T_(p) and a drain current Id thereof in FIG. 4.

In FIG. 5, horizontal axis represents the source-gate voltage Vsg of thetriode T_(p), longitudinal axis represents the drain current Id thereof.Curves 1 and 2 in FIG. 5 show the source-gate voltage Vsg and the draincurrent Id when the source-drain voltage Vsd are at Vsd1 and Vsd2 (Vsd1is greater than Vsd2), respectively. When the gate of the triode T_(p)is clamped at the predetermined voltage, the gate voltage of thetransistor is promoted, the source-gate voltage Vsg decreases, thesource-drain voltage Vsd at the same drain current Id increases, andcorrespondingly, the resistance value of the triode T_(p) increases.

It can be seen from the illustration of FIG. 5 that, when thepredetermined voltage at which the gate (i.e., point Pgate in FIG. 4) ofthe triode T_(p) is clamped varies, i.e. the clamping voltage varies,the resistance value of the triode T_(p) changes correspondingly. Thehigher the clamping voltage is, the greater the resistance value of thetriode T_(p) is; the lower the clamping voltage is, the smaller theresistance value of the triode T_(p) is. When the resistance value ofthe triode T_(p) is large, overcurrent protection can be achievedquickly.

In order to facilitate the achievement, the gate of the triode T_(p) maybe clamped at the input voltage Vin of the synchronous boost converter,and in such a configuration, it is not necessary to provide other supplyvoltages to the synchronous boost converter. In addition, the gate ofthe triode T_(p) may be clamped at a preset voltage lower than the inputvoltage Vin.

FIGS. 6(a) and 6(h) schematically illustrate a circuit diagram of theclamping unit 131 in the overcurrent protection device shown in FIG. 4.

In FIG. 6(a), the clamping unit 131 includes series-connected triodes T1and T2, wherein the source of the triode T1 is connected to the inputvoltage Vin, the gate of the triode T1 is connected to its drain, andconnected to the source of the triode T2, the drain of the triode T2 isconnected to the gate (point Pgate in FIG. 4) of the triode T_(p), i.e.,drain voltage of the triode T2 is equal to gate voltage Vg of the triodeT_(p), and the gate of the triode T2 is turned on or turned oft underthe driving of the overcurrent indication signal OCE. When theovercurrent indication signal OCE is enabled, the triode T2 is turnedon, the source-gate voltage Vsg of the triode T1 is equal to itssource-drain voltage Vsd, the gate voltage Vg of the triode T_(p) isequal to the input voltage Vin minus the source-gate voltage Vsg oftriode T1. When the overcurrent indication signal OCE is disabled, thetriode T2 is turned off, an open circuit is formed between the gate ofthe triode T_(p) and the input voltage Vin, so as to not clamp the gatevoltage of the triode T_(p).

In FIG. 6(b), the clamping unit 131 includes a triode T3, whose sourceis connected to the input voltage Vin and whose drain is connected tothe gate of the triode T_(p), the gate of the triode T3 can be turned onor turned off under the driving of the overcurrent indication signalOCE. When the overcurrent indication signal OCE is enabled, the triodeT3 is turned on, the drain voltage of the triode T3 is equal to theinput voltage Vin, i.e., the gate voltage Vg of the triode T_(p) isclamped at the input voltage Vin. When the overcurrent indication signalOCE is disabled, the triode T3 is turned off, an open path is formedbetween the gate of the triode T_(p) and the input voltage Vin, so as tonot clamp the gate voltage of the triode T_(p).

The second driving unit may be made to output a high level consistentlywhile the clamping unit 131 clamps the gate voltage of the triode T_(p),in this case, the clamping voltage of the gate of the triode T_(p) willbe affected by the high level output by the second driving unit.Alternatively, the second driving unit may be made to disconnect thegate of the triode T_(p), so as to clamp the gate voltage Vg of thetriode T_(p) at a desired voltage.

As an example of disconnecting the second driving unit with the gate oftriode T_(p), it is possible to set a switch driven by using theovercurrent indication signal OCE between the traditional second drivingunit and the gate of the triode T_(p). When the overcurrent OCE signalindicates that no overcurrent event occurs, the switch is in a closedstate, the second driving unit drives the triode T_(p) to turn on orturn off in the traditional way; when the overcurrent indication signalOCE indicates an overcurrent event occurs, the OCE overcurrentindication signal drives the switch to open, so that an open path isformed between the second driving unit and the gate of the triode T_(p).Alternatively, the second driving unit may be also made to present ahigh impedance with respect to the gate of the second triode when theovercurrent indication signal OCE indicates that an overcurrent eventoccurs, which will be described in conjunction with FIG. 7.

FIG. 7 schematically illustrates a circuit diagram of a second drivingunit in the overcurrent protection device shown in FIG. 4. In FIG. 7,the second driving unit receives the overcurrent indication signal OCEand a control signal Sc for instructing the triode T_(p) to turn on orturn off. Inverters (INV1-INV7), “NOR” gates (NOR4, NOR5), “AND” gates(AND1, AND2) are used for performing logic operations on the overcurrentindication signal OCE and the control signal Sc, and a driving signal isoutput through a triode T4 and a triode T5. FIG. 7 shows specificexample of a connection relationship. When the overcurrent indicationsignal OCE indicates that no overcurrent event occurs, the triode T4 andthe triode T5 in FIG. 7 output 0 or 1 under control of the controlsignal Sc, for example, when the triode T4 turns off and the triode T5turns on under action of the control signal Sc, the second driving unitin FIG. 7 outputs a driving signal “0” to cause the triode T_(p) to turnoff; when the triode T4 turns on and the triode T5 turns off underaction of the control signal Sc, the second driving unit in FIG. 7outputs a driving signal ‘1’ to turn on the triode T_(p). When theovercurrent indication signal OCE indicates that an overcurrent eventoccurs, both the triode T4 and triode T5 in FIG. 7 turn off under actionof the overcurrent indication signal OCE, output of the second drivingunit is a high impedance, which does not affect the clamping voltage atthe gate of triode T_(p).

In addition, the synchronous boost converter may also adopt thestructure of the overcurrent protection device 200 shown in FIG. 2, inthis case, the second driving unit drives the triode T_(p) in aconventional manner, the overcurrent detection unit 110 supplies theovercurrent indication signal OCE to the switch S to control whether toconsume electricity on the electricity transmission path by the resistorR.

FIG. 8 illustrates a schematic waveform of performing overcurrentprotection by the overcurrent protection device in FIG. 4 in thesynchronous boost converter. In FIG. 8, horizontal axis represents time,longitudinal axis in FIG. 8(a) represents voltage, and FIG. 8(a) showscurves of the input voltage Vin and the output voltage Vout;longitudinal axis in FIG. 8(b) represents current, and FIG. 8(b) shows acurve of current of a load supplied by the output voltage Vout;longitudinal axis of FIG. 8(c) represents voltage of the overcurrentindication signal OCE output by the overcurrent detection unit 110,wherein when the overcurrent indication signal OCE appears as a lowvalue, it indicates that an overcurrent event occurs; longitudinal axisof FIG. 8(d) represents voltage, and FIG. 8 (d) shows a curve of voltageat the point SW in FIG. 4, which reflects a switching frequency of thesynchronous boost converter. As can be seen, when an overcurrent eventoccurs as the input voltage Vin is close to the output voltage Vout, theoutput voltage Vout and load current can be reduced effectively by theovercurrent protection device of the present application, thusovercurrent protection is achieved (as shown by the ellipse blocks inFIGS. 8 (a) and 8(b)).

From the description provided above with reference to FIGS. 4-8 it canbe known that, when an overcurrent event occurs, as compared with aconfiguration where only the inductor L is controlled to no longer storethe input electricity in the conventional technology, an existing triodeof the synchronous boost converter is also used for forming anelectricity consumption element to consume electricity stored in theinductor L in the electricity transmission path. Even if the outputvoltage in the synchronous boost converter is close to or less than theinput voltage, the electricity consumption element formed by the triodecan also be used for effectively reducing the current in the boostconverter and achieve overcurrent protection.

FIG. 9 illustrates a flowchart of an example overcurrent protectionmethod 900 in the present application. The overcurrent protection method900 may be used for the electronic module as follows and electronicapparatus including the electronic module. The electronic module mayinclude: an electricity storage unit for temporarily storing inputelectricity and capable of releasing the stored electricity through anelectricity transmission path; and an electricity storage control unitfor controlling storage and release of electricity in the electricitystorage unit. The electronic module for example is a voltage converter,an amplifier, a monitor, etc., and any electronic module including theelectricity storage unit and the electricity storage control unit mayadopt the overcurrent protection device of the present application. Inaddition, the electronic module may also include other units orsections, for example, the voltage converter may further include afeedback unit for performing feedback control based on an output signal,a voltage stabilizing unit for stabilizing an output voltage, and adriving unit for driving the electricity storage control unit etc.

As shown in FIG. 9, the overcurrent protection method 900 for theelectronic module may comprise: determining whether an overcurrent eventoccurs in the electronic module, and generating an overcurrentindication signal OCE indicative of whether the overcurrent event occurs(S910); supplying the overcurrent indication signal OCE to theelectricity storage control unit for controlling the electricity storageunit to release electricity when the overcurrent event occurs (S920);setting an electricity consumption unit removably connected in theelectricity transmission path and capable of consuming electricity thatpasses through the electricity transmission path while being connectedin the electricity transmission path (S930); and controlling connectionof the electricity consumption unit in the electricity transmission pathbased on the overcurrent indication signal OCE (S940).

When the overcurrent indication signal OCE generated in S910 indicatesthat an overcurrent event occurs, the electricity storage control unitcontrols the electricity storage unit to release electricity and nolonger receive more electricity in S920, the power consumption unit isconnected in the electricity transmission path in S930 and S940 in orderto consume electricity, thereby avoiding a continued increase of thecurrent output by the electricity storage unit, and accordingly protectthe electricity storage unit and the electricity storage control unitand electronic elements in the electricity release path from beingdestroyed.

In S930 a resistor may be provided in the electricity transmission pathas the electricity consumption unit, with a switch connected in parallelwith the resistor being set therein, change of the operating state ofthe switch can cause the resistor to reside in the electricitytransmission path or be excluded from the electricity transmission path.In particular, when the overcurrent indication signal OCE indicates thatan overcurrent event occurs, the switch connected in parallel with theresistor is opened in S940, correspondingly, the resistor resides in theelectricity transmission path to consume electricity; when theovercurrent indication signal OCE indicates that no overcurrent eventoccurs, the switch in parallel with the resistor is closed in S940 toform a short circuit, the resistor is excluded from the powertransmission path.

Further, in the case that there is a triode (e.g., the triode T_(p) inFIG. 4) in the electricity transmission path, the electricityconsumption unit may be implemented by using the triode in S930, withoutthe need to set an electricity consumption unit specifically.Accordingly, in S940, the gate of the triode in the electricitytransmission path is clamped at a high voltage, so that the triodepresents resistive properties, and consumes electricity in theelectricity transmission path. The high voltage may be the input voltagein the boost converter or a predetermined voltage lower than the inputvoltage. For more flexibility clamping the gate of the triode at adesired high voltage, the gate of the triode may be disconnected withits driving signal when an overcurrent event occurs. Disconnection ofthe gate of the triode and its driving signal may be implemented via aswitch, or may also be implemented by causing the driving unit forgenerating the driving signal to generate a high output impedance.

In the overcurrent protection method of the present application, when anovercurrent event occurs, the electricity consumption unit is furtherprovided on the electricity transmission path where the electricitystorage unit releases electricity, and electricity stored in theelectricity storage unit is also consumed by the electricity consumptionunit, thus reducing the current flowing through the circuit module andachieving overcurrent protection. Even if the output voltage in theboost converter is close to or less than the input voltage, theelectricity consumption unit can also be used for effectively reducingthe current in the boost converter and achieving efficient overcurrentprotection.

In the various examples described herein, references are made totriodes. It will be understood that such triodes can include transistorssuch as field-effect transistors (FETs). Such FETs can include, forexample, MOSFET devices and/or transistors implemented in other processtechnologies. Other types of transistors can be utilized to implementone or more features of the present disclosure.

Those skilled in the art can understand, for convenience and simplicityof the description, as for specific implementations of the methodembodiments described above, corresponding process in the precedingproduct embodiments can be implemented.

Those with ordinary skill in the art can appreciate that, devices andalgorithm steps described with reference to the embodiments disclosed inthis document may be implemented through electronic hardware, or acombination of the electronic hardware and software. As for eachspecific application, a person skilled in the art can use differentmethods to implement the described functions, but such implementationsshould not be construed as being beyond the scope of the presentinvention.

Principles and advantages of technical solutions described above areapplicable to any system and module that require overcurrent protection.The system and module having the overcurrent protection can be realizedin a variety of electronic apparatuses, which may include, but not arelimited to, an electronic product, a portion of an electronic product,an electronic test equipment etc. The consumer electronic product mayinclude, but is not limited to, a smart phone, a TV a tablet computer, amonitor, a personal digital assistant, a camera, an audio player, amemory etc. A portion of the consumer electronic product may include amulti-chip module, a power amplifier module, a voltage converter etc.

The above described are only specific implementations of the presenttechnical solution, but the scope of the present technical solution isnot limited thereto, and any alternatives and equivalents that can beconceivable by a person skilled in the art should be encompassed withinthe scope of protection of the present technical solution.

What is claimed is:
 1. A voltage converter comprising: a voltageconverting circuit configured to receive an input voltage and generatean output voltage, and including an input inductor and an outputcapacitor; and a protection circuit including a detection unitconfigured to detect an overcurrent condition based on a current throughthe input inductor, the detection unit further configured to provide anovercurrent signal indicative of the overcurrent condition to a drivingunit of the voltage converting circuit to cease charging operation andto perform discharging operation while the overcurrent condition exists,the protection circuit further including a consumption unit implementedalong an electrical path of the voltage converting circuit andconfigured to provide a first consumption value when there is noovercurrent condition and a second consumption value during theovercurrent condition, the second consumption value greater than thefirst consumption value, such that the consumption unit selectivelyprovides an increased consumption value along the electrical path duringthe overcurrent condition.
 2. The voltage converter of claim 1 whereinthe detection unit is further configured to generate an overcurrentsignal indicative of the overcurrent condition, and the consumption unitis configured to provide the second consumption value when theovercurrent signal is present, and provide the first consumption valuewhen the overcurrent signal is absent.
 3. The voltage converter of claim1 wherein the consumption unit is configured to consume substantiallynone of a current passing through the electrical path when theovercurrent condition is absent.
 4. The voltage converter of claim 1wherein the electrical path is an output path of the voltage convertingcircuit.
 5. The voltage converter of claim 1 wherein the detection unitincludes a current sensor configured to generate a sensed voltage basedon the current through the input inductor.
 6. The voltage converter ofclaim 5 wherein the detection unit further includes a comparatorconfigured to compare the sensed voltage with a reference voltage toprovide a comparator-output signal.
 7. The voltage converter of claim 6wherein the detection unit further includes a logic circuit configuredto combine the comparator-output signal and a clock signal to providethe overcurrent signal, such that the overcurrent signal issubstantially synchronized with the clock signal.
 8. The voltageconverter of claim 1 wherein the consumption unit includes a switchableresistance configured to provide a first resistance as the firstconsumption value when there is no overcurrent condition and a secondresistance as the second consumption value during the overcurrentcondition.
 9. The voltage converter of claim 8 wherein the firstresistance includes a resistance associated with an output path of thevoltage converting circuit during normal operation when there is noovercurrent condition.
 10. The voltage converter of claim 9 wherein theswitchable resistance includes a parallel combination of a resistor anda switch implemented along the output path, the switch configured to bein an open state during the overcurrent condition to allow the resistorto consume at least some of a current in the output path, the switchfurther configured to be in a closed state when there is no overcurrentcondition.
 11. The voltage converter of claim 1 wherein the voltageconverting circuit is configured to operate as an asynchronous boostconverter.
 12. The voltage converter of claim 1 wherein the consumptionunit includes a transistor configured to provide a first resistance asthe first consumption value when there is no overcurrent condition and asecond resistance as the second consumption value during the overcurrentcondition.
 13. The voltage converter of claim 12 wherein the protectioncircuit further includes a clamping unit configured to control thetransistor to provide the second resistance during the overcurrentcondition.
 14. The voltage converter of claim 12 wherein the voltageconverting circuit is configured to operate as a synchronous boostconverter.
 15. A method for operating a voltage converter that includesan input inductor and an output capacitor, the method comprising:converting an input voltage to an output voltage; detecting anovercurrent condition based on a current through the input inductor;providing an overcurrent signal indicative of the overcurrent conditionto a driving unit of the voltage converting circuit to cease chargingoperation and to perform discharging operation while the overcurrentcondition exists; and controlling a consumption unit along an electricalpath associated with the converting of the input voltage to the outputvoltage, to provide a first consumption value when there is noovercurrent condition and a second consumption value during theovercurrent condition, the second consumption value greater than thefirst consumption value, such that the consumption unit selectivelyprovides an increased consumption value along the electrical path duringthe overcurrent condition.
 16. The method of claim 15 wherein theconsumption unit consumes substantially nil amount of current when thereis no overcurrent condition.
 17. A portable electronic devicecomprising: a module configured to utilize a regulated voltage; and avoltage converter configured to provide the regulated voltage, thevoltage converter including a voltage converting circuit and aprotection circuit, the voltage converting circuit including an inputinductor and an output capacitor, the protection circuit including adetection unit configured to detect an overcurrent condition based on acurrent through the input inductor, the detection unit furtherconfigured to provide an overcurrent signal indicative of theovercurrent condition to a driving unit of the voltage convertingcircuit to cease charging operation and to perform discharging operationwhile the overcurrent condition exists, the protection circuit furtherincluding a consumption unit implemented along an electrical path of thevoltage converting circuit and configured to provide a first consumptionvalue when there is no overcurrent condition and a second consumptionvalue during the overcurrent condition, the second consumption valuegreater than the first consumption value, such that the consumption unitselectively provides an increased consumption value along the electricalpath during the overcurrent condition.
 18. The portable electronicdevice of claim 17 wherein the portable device includes a mobile phone,a tablet computer, a display, an eBook reader, or a portable digitalmedia display.